1. Field of the Invention
The present invention relates generally to environmental control systems for heating, ventilating, humidifying and air conditioning equipment, and, more particularly, to a new and improved kit including a thermostat or remote control unit located in a living space of a house and a main control unit located in the vicinity of the heating, ventilating, humidifying and air conditioning equipment that enables the remote control unit to separately control via existing four wire circuits the heating, ventilating, humidifying and air conditioning equipment.
2. Description of the Prior Art
In many conventional household forced air heating, ventilating and air conditioning systems (commonly referred to as HVAC systems), heated or cooled forced air is supplied by a blower fan in a furnace to the different living spaces within the house. Humidification of that living space also is desirable because a low level of humidity can result in static shocks and drying of a person's respiratory track. Moreover, moisture in the living space tends to retain heat resulting in the temperature being more uniformly maintained in the living space. The addition of moisture to a dry and hot living space also can be used to reduce the air temperature in the living space due to the fact that the moisture absorbs heat.
The humidification of the forced air being supplied to the living spaces in a forced air system usually is accomplished by means of a humidifier that is slaved to the blower fan of the HVAC system. On the other hand, the blower fan is dependent upon the operation of the furnace so that humidification tends to be provided to the living spaces of a house only when the temperature in the living spaces is being adjusted. As a result, the humidity in the living space may be less than optimum. In fact, little, if any, humidification will be provided to the living spaces when the outside air temperature and the thermostat setting for the inside living spaces are about the same. Yet the living spaces might still need additional humidification so that a condition of low humidity in the living spaces of the house can occur.
Accordingly, it would be advantageous to have an environmental control system that permits the humidification in the living spaces to be separately controlled independent of the heating and cooling functions. However, most HVAC systems only have four wires extending from the thermostat located in the living space and the furnace and/or air conditioner units. With such a four wire system, the humidifier typically is slaved to the furnace blower and not separately controlled because additional wires would be needed to provide such independent control of the humidifier. In fact, certain systems have accomplished independent control of a humidifier by extending six wires from the living space (thermostat) to the furnace and air conditioner. Unfortunately, such six-wire systems cannot be utilized unless the existing four wire system is rewired.
A humidity control system is disclosed in U.S. Pat. No. 4,974,665 that issued on Dec. 4, 1990 to the inventor of the present application. The control system disclosed in that patent provides for controlling of the heating and air conditioning independently of ventilation and humidification. This independent control is accomplished even though only a four-wire link extends between temperature and fan/humidity controls located in the living space and the heating, air conditioning, ventilation and humidification equipment located in a plant/furnace area of the house. However, this system requires that the output of a typical AC transformer used in a heating system be full-wave rectified before the potential is supplied to the remote control unit. Moreover, the fan and humidifier control are combined into one switch so that the fan for ventilation cannot be independently controlled when the humidity is being controlled. In other words, the system does not permit the fan to be activated continuously while the humidity is being controlled.
Another heating/cooling control system is disclosed in U.S. Pat. No. 4,083,397 issued on Apr. 11, 1978. This system enables the heating and cooling functions to be controlled even though only two wires extend between an thermostat and the heating and air conditioning equipment. However, this system does not provide for the separate control of humidification equipment or the furnace blower fan.